1. Field of the Invention
The present invention relates to a dust collector for collecting fine dust in air. More particularly, the present invention relates to a dust collector for collecting fine dust in air, which is used with an air supply assembly for supplying the air through a duct, and can efficiently collect dust or fine particles to clean the
2. Description Related to the Prior Art
There are various types of dust collectors, of which an example is disclosed in U.S. Pat. No. 6,193,788 (corresponding to JP-A 10-249235). A plurality of needle electrodes charges floating fine particles in air by causing corona discharge in the periphery of their needle ends. A plurality of cell-shaped collecting electrodes attract and collect the particles electrostatically after charging by the needle electrodes.
JP-A 10-323580 discloses a frictional electrification device in which objects are charged at an amount required for classifying target crushed trash including plastic material. The frictional electrification device includes an outer container, and an inner container disposed in the outer container in a rotatable and vibratile manner. An agitation blade is disposed in the inner container, for rotating in a direction backward to that of the inner container. When the inner container is supplied with the target crushed trash, the agitation blade mover the target crushed trash toward the trash exit port successively. Electric charge is generated by frictional contact of the inner container with the agitation blade in rotation and vibration, and also by frictional contact between pieces of the target crushed trash. According to a triboelectric series including related substances, the target crushed trash with particular characteristics is charged positively or negatively, and then is exited through a trash exit port. Note that the triboelectric series is a train of substances obtained in such a manner that, when two substances are combined as a pair and frictionally contacted by one another, one is charged positively, the remainder being charged negatively, and that numerous substances are arranged according to the electrically negative and positive characteristics after experiments.
However, the dust collector of the first of the two documents has shortcomings. Because a direct-current power source of high voltage is required, manual handling of the dust collector is dangerous to users. Also, a manufacturing cost is considerably high. Furthermore, the frictional electrification device of the second of the two documents has problems. Electric charge is generated nearly in entirety of the inside of the inner container by the charging operation. For the periodical maintenance after repeated use, large regions in the frictional electrification device should be cleaned, including an inner surface of the inner container and a surface of the agitation blade. However, no disassembly of the outer container of the inner container is disclosed in the document. To clean and maintain the frictional electrification device requires much time and laborious operation.
In view of the foregoing problems, an object of the present invention is to provide a dust collector for collecting fine dust in air, capable of collecting floating fine particles safely and also at a lost cost.
Another object of the present invention is to provide a dust collector for collecting fine dust in air, capable of being cleaned with great ease.
In order to achieve the above and other objects and advantages of this invention, a dust collector for collecting fine dust in air and for cleaning the air is provided. A first friction member is produced from a first substance. A second friction member is produced from a second substance that is chargeable triboelectrically in a polarity different from a polarity of the first substance. A friction driving mechanism moves one of the first and second friction members relative to a remaining one thereof, and frictionally generates electrostatic charge, to attract the fine dust.
In other words, a first friction device is produced from a first substance. A second friction device is produced from a second substance which is in a different position from the first substance in a triboelectric series of substances, for frictionally contacting the first friction device. A moving mechanism moves one of the first and second friction devices relative to a remaining one thereof, to generate electrostatic charge by charging the first and second friction devices, so as to attract the fine dust.
The first substance is polytetrafluoroethylene.
At least one of the first and second substances has a surface resistance of 109 xcexa9 or higher.
Furthermore, there is a passage case for flowing through of the air, the first and second friction devices contact one another inside the passage case. A fan sends the air through the passage case.
The first and second friction devices have a plate shape, the first friction device is stationary with the passage case. The moving mechanism moves the second friction device.
The first and second substances have such characteristics as to be charged respectively in negative and positive states when frictionally contacted on one another.
The fan sends the air from an air intake port of the passage case to an air, exhaust port thereof. Furthermore, a filter is disposed in the air intake, port, for preventing dust from entry therein.
The moving mechanism includes a motor for rotating the second friction device.
The first friction device is secured to a case panel of the passage case.
Furthermore, an access opening is formed in the passage case, and provided with the first friction device secured to an inside thereof. A fastener retains the first friction device in the access opening, the fastener being detached for cleaning or maintaining the first and second friction devices, to allow removal of the first friction device from the access opening.
Furthermore, one case panel in provided with the first friction device secured thereto, retained in the access opening by the fastener, for closing the access opening.
Furthermore, a biasing mechanism presses the second friction device against the first friction device.
The case panel is a lower panel of the passage case disposed on a downside.
In a preferred embodiment, the case panel comprises a lower panel and au upper panel of the passage case disposed on respectively a downside and upside. First and second electrostatic generator units are disposed in respectively the lower and upper panels, each of the first and second electrostatic generator units being constituted by the first and second friction devices.
Furthermore, first and second axial holes are formed through respectively the case panel and the first friction device. The motor is disposed outside the case panel, has an output shaft extending through the first and second axial holes, for rotating the second friction device.
The air is supplied to a thermal bead of a thermal printer by the fan through the passage case, to cool the thermal head.
The second friction device has a disk shape.
The second substance is polypropylene.
In another preferred embodiment, furthermore, a dust eliminating portion rubs away the fine dust stuck on the first or second friction device.
The moving mechanism includes a motor for rotating the second friction device. The dust eliminating portion is a dust eliminating edge portion of the second friction device, extending in a direction away from a rotational center thereof, for rubbing the first friction device in rotation of the second friction device, to eliminate the fine dust stuck on the first or second friction device.
The first and second friction devices are disposed in an upper panel of the passage case disposed on an upside. Furthermore, a dust exit path is formed in a downside of the passage case, for passing down the fine dust from the dust eliminating portion, to exit the fine dust.
Furthermore, a dust containing case is disposed under the dust exit path, for receiving the fine dust to be abandoned.
The passage case includes an intermediate casing frame, has the dust exit path, and in which the first and second friction devices contact one another. An upstream casing frame is connected with the intermediate casing frame on an upstream side, for containing the filter. A downstream casing frame is connected with the intermediate casing frame on a downstream side, for containing the fan.
The first friction device is the intermediate casing frame.
Furthermore, a first shutter openably closes a path of the air extending from the air intake port toward the air exhaust port. A second shutter closes the dust exit path openably. A controller opens and closes the first and second shutters alternately, drives the fan to eject the air from the passage case while the second shutter is closed and the first shutter is open, and drives the moving mechanism to attract the fine dust while the first shutter is closed and the second shutter is open.
The controller measures driving time of driving the moving mechanism, and when the driving time increases to become a predetermined time, stops driving the moving mechanism, and closes the second shutter.
The controller measures elapsed time elapsed after stopping driving the moving mechanism, and when the elapsed time increases to become a predetermined limit time, stops driving the fan, and closes the first shutter.
At a time of powering, the controller closes the first shutter, opens the second shutter, and also drives the moving mechanism to attract the fine dust.
A surface resistance of the intermediate casing frame is higher than a surface resistance of the upstream and downstream casing frames, and is 109 xcexa9 or higher.
In a further preferred embodiment, the second friction device has a peripheral edge of which at least one portion extends in a direction away from a rotational center thereof, and constitutes the dust eliminating edge portion.
In another preferred embodiment, the second friction device includes a rotatable plate or disk. At least one opening is formed in the plate or disk, has an inner edge portion including the dust eliminating edge portion.
The at least one opening is plural openings.
In still another preferred embodiment, the second friction device has at least one arm disposed to extend in a direction away from a rotational center thereof, the arm having the dust eliminating edge portion.